A radiology information system (RIS) used in a hospital typically employs the Health Level 7 (HL7) international standard for messaging that defines a series of healthcare events, records and messages to support administrative, logistical, financial as well as clinical processes. HL7 is not designed to support the exchange of image data. HL7 messages are broadcast on internal and inter-hospital networks to indicate events such as the admission, discharge or transfer of a patient, or, for example, to record the fact that the results of a Diagnostic Imaging (DI) test have been recorded in the RIS. The HL7 data stored in the RIS may include fields such as patient ID, patient name, gender and address, date and time of admission, name of referring physician, name of radiologist, as well as test-specific information. For example, if a magnetic resonance (MR) study has been requested for a patient, then the HL7 data for that patient may indicate the procedure code for such a request, the requesting physician, imaging status and report status.
Diagnostic image data is typically handled by a picture archiving and communication system (PACS). PACS systems generally store and transmit data in accordance with the Digital Imaging and Communications in Medicine (DICOM) international standard. Imaging modalities, such as MR and other diagnostic imaging devices, generally communicate directly with the PACS over a network using DICOM. The function of the PACS is to maintain a database of diagnostic images taken on connected devices along with related information for image display and patient demographics.
In addition to the image data, the DICOM records include accession number, the start and end times of tests, demographic information such as patient identification information, and may include identification of the attending staff member(s).
Information must be transmitted between such RIS and PACS systems and DI modality devices, for example, in order to indicate which tests have been ordered on which patients, and report when image studies have been completed.
For example, after an MR test has been completed, the interpreting radiologist will render a medical opinion report on the images, which is stored the RIS and PACS in one of several possible different formats.
The lack of interoperability between HL7 and DICOM has been a longstanding problem as is the variability in the use and interpretation of these standards. Manual transfer of data is expensive and error-prone. There have been attempts to harmonize the standards using integration profiles (IP's) to achieve specific interoperability, which has been led by an organization known as IHE (integrating the healthcare enterprise) working group. Unfortunately, these have been of limited success and achieved only limited interoperability. Some automated approaches have been employed such as the use of a “broker” system or software to translate between the two protocols so that a RIS can communicate directly with a modality (such as MR) and/or PACS. However, such solutions are expensive, and are error-prone because of the varying interpretations and use of the standards.
After the modality and/or PACS information is made available to the RIS and incorporated into the RIS database, the RIS may then be able to produce reports relating to the use of the imaging modalities and use of staff. For example, the RIS may provide aggregated monthly reports on the total number of ultrasound tests completed, the total technical fees, professional fees and workload units claimed for each month. This may be accompanied with variances from the previous year and the current budget. Reports showing the total workload units on a modality by modality basis or other aggregated basis for a certain period are also typically produced four to six weeks after the period.
It may be very useful to compare such information across multiple hospitals so each hospital can identify efficiencies or deficiencies in its utilization of imaging modalities and take corrective action. Such comparisons are very difficult because the procedure (study) code dictionaries are not standardized and are used differently by different hospitals. The Canadian Institute for Health Information (CIHI) provides a set of standardized code guidelines for hospital workload units for every procedure completed in health care in Canada. However, hospitals vary from these guidelines. When CIHI suggests 12 workload units to complete a two view chest radiography study and the hospital consistently takes 18 workload units to complete the study, then the hospital will change its own procedural dictionary to 18 workload units. In addition, the combination of certain studies into a single exploding code for convenience varies from hospital to hospital depending on the radiologists' preferences for study grouping. This makes the standardization of study dictionaries more difficult.